﻿#define _CRT_SECURE_NO_WARNINGS 1

//编程初学者入门训练第115题
//BC117 小乐乐走台阶
//https://www.nowcoder.com/practice/ebf04de0e02c486099d78b7c3aaec255?tpId=107&tqId=33398&rp=1&ru=/exam/oj/ta&qru=/exam/oj/ta&sourceUrl=%2Fexam%2Foj%2Fta%3Fpage%3D3%26tpId%3D107%26type%3D107&difficulty=undefined&judgeStatus=undefined&tags=&title=

#include <stdio.h>

//递归解决
int Fib(int n)
{
    if (n <= 2)
    {
        return n;
    }
    else
    {
        return Fib(n - 1) + Fib(n - 2);
    }
}

int main()
{
    int n = 0;
    scanf("%d", &n);
    int ret = Fib(n);

    printf("%d\n", ret);

    return 0;
}